News from the world of Maths

In the corner of the garden between the Centre of Mathematical Sciences and the Isaac Newton Institute in Cambridge, sits a reminder of our ongoing quest to understand gravity: an apple tree that was taken as a cutting from the tree at Newton's birthplace, the tree that is said to have inspired his theory of gravity. Newton's theory was extended to the cosmological scales by Einstein's theory of general relativity – but can supergravity explain how gravity works in the quantum world?

"Astronomers are used to large numbers, but few are as large as the odds I'd have given this celebration today," is how Astronomer Royal Martin Rees started his presentation at Stephen Hawking's birthday symposium yesterday. He was talking about the 1960s when he first met Hawking who was then already suffering motor neurone disease. But Rees' prediction has been proved wrong. Hawking turned 70
yesterday and since the time of their first meeting he has made enormous contributions to cosmology and physics.

It's Stephen Hawking's 70th birthday this week and the University of Cambridge is celebrating with a conference in his honour. If it's going to be as exciting as his 60th birthday, and it definitely looks like it will, then we're in for a treat! We'll be giving you articles and podcasts from the conference soon, but in the meantime, here's what we did for his 60th.

Human reasoning is biased and illogical. At least that's what a huge body of psychological research seems to show. But now a psychological scientist from the University of Toulouse in France has come up with a new theory: that logical and probabilistic thinking is an intuitive part of decision making, only its conclusions often lose out to heuristic considerations.

This is it! Merry Christmas to all you beautiful Plus readers and listeners from the Plus team! We hope you'll have a marvellously happy 2012! And since Christmas is all about getting together with the folks, here's some family maths. You might not be able to choose them, but at least you can analyse them!

Christmas is a time of mysteries so we thought we'll give you the chance to put your favourite mystery to the experts. Pick a question in the poll on the right — after Christmas we'll answer the most popular question in articles and podcasts based on interviews with physicists and mathematicians who really know about these things.